Re: [PATCH v2 2/6] driver core: Add common support to skip probe for un-authorized devices
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2021-09-30 10:59:48
Also in:
linux-pci, linux-usb, lkml
On Wed, Sep 29, 2021 at 06:05:07PM -0700, Kuppuswamy Sathyanarayanan wrote:
While the common case for device-authorization is to skip probe of unauthorized devices, some buses may still want to emit a message on probe failure (Thunderbolt), or base probe failures on the authorization status of a related device like a parent (USB). So add an option (has_probe_authorization) in struct bus_type for the bus driver to own probe authorization policy. Reviewed-by: Dan Williams <redacted> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
So what e.g. the PCI patch https://lore.kernel.org/all/CACK8Z6E8pjVeC934oFgr=VB3pULx_GyT2NkzAogdRQJ9TKSX9A@mail.gmail.com/ (local) actually proposes is a list of allowed drivers, not devices. Doing it at the device level has disadvantages, for example some devices might have a legacy unsafe driver, or an out of tree driver. It also does not address drivers that poke at hardware during init. Accordingly, I think the right thing to do is to skip driver init for disallowed drivers, not skip probe for specific devices.
quoted hunk
--- drivers/base/dd.c | 5 +++++ drivers/thunderbolt/domain.c | 1 + drivers/usb/core/driver.c | 1 + include/linux/device/bus.h | 4 ++++ 4 files changed, 11 insertions(+)diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 68ea1f949daa..0cd03ac7d3b1 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c@@ -544,6 +544,11 @@ static int really_probe(struct device *dev, struct device_driver *drv) !drv->suppress_bind_attrs; int ret; + if (!dev->authorized && !dev->bus->has_probe_authorization) { + dev_dbg(dev, "Device is not authorized\n"); + return -ENODEV; + } + if (defer_all_probes) { /* * Value of defer_all_probes can be set only bydiff --git a/drivers/thunderbolt/domain.c b/drivers/thunderbolt/domain.c index 3e39686eff14..6de8a366b796 100644 --- a/drivers/thunderbolt/domain.c +++ b/drivers/thunderbolt/domain.c@@ -321,6 +321,7 @@ struct bus_type tb_bus_type = { .probe = tb_service_probe, .remove = tb_service_remove, .shutdown = tb_service_shutdown, + .has_probe_authorization = true, }; static void tb_domain_release(struct device *dev)diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c index fb476665f52d..f57b5a7a90ca 100644 --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c@@ -2028,4 +2028,5 @@ struct bus_type usb_bus_type = { .match = usb_device_match, .uevent = usb_uevent, .need_parent_lock = true, + .has_probe_authorization = true, };diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index 062777a45a74..571a2f6e7c1d 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h@@ -69,6 +69,9 @@ struct fwnode_handle; * @lock_key: Lock class key for use by the lock validator * @need_parent_lock: When probing or removing a device on this bus, the * device core should lock the device's parent. + * @has_probe_authorization: Set true to indicate to the driver-core to skip + * the authorization checks and let bus drivers + * handle it locally. * * A bus is a channel between the processor and one or more devices. For the * purposes of the device model, all devices are connected via a bus, even if@@ -112,6 +115,7 @@ struct bus_type { struct lock_class_key lock_key; bool need_parent_lock; + bool has_probe_authorization; }; extern int __must_check bus_register(struct bus_type *bus);-- 2.25.1
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